3GPP (The 3rd Generation Partner Project) standardization organization is working out the next generation of wireless communication standard which is named LTE (Long Term Evolution). In a physical layer interface, new standard adopts OFDM (Orthogonal Frequency Division Multiplexing) technology, which is different from conventional CDMA (Code Division Multiple Access) technology. In LTE, OFDMA (Orthogonal Frequency Division Multiple Access) is used in downlinks (DL) and SC-FDMA (Single Carrier Frequency Division Multiple Access) is used in uplinks (UL). The technology used in the new standard is effective for multi-path propagation, with adoption of frequency domain equalization reducing complexity of the conventional time domain equalization, and is more suitable for wider bandwidth high-speed data transmission.
According to the current standardization of LTE (see Non-Patent Document 1 below), PUCCH assignment includes two cases. In case of a PDSCH (Physical Downlink Shared Channel) transmission indicated by the detection of a corresponding PDCCH (Physical Downlink Control Channel) in subframe n−4, or for a PDCCH indicating downlink SPS (Semi-Persistent Scheduling) release in subframe n−4, the UE (User Equipment) shall use PUCCH resource nPUCCH(1)=nCCE+NPUCCH(1) for transmission of HARQ (Hybrid Automatic Repeat reQuest)-ACK (ACKnowledge)/NACK (Negative ACKnowledge) in subframe n, where nCCE is the number of the first CCE (Control Channel Element) used for transmission of corresponding DCI (Downlink Control Information) assignment and NPUCCH(1) is a parameter configured cell-specifically by higher layer signaling. In case of a PDSCH transmission where there is not a corresponding PDCCH detected in subframe n−4, the PUCCH resource, i.e., the value of nPUCCG(1), is determined according to 4 PUCCH resource candidates transmitted by higher layer signaling and the PUCCH resource index transmitted in the DCI format, which indicates a semi-persistent downlink scheduling activation.
The 3GPP is also working out LTE-Advanced (Advanced-LTE) which is likely major enhancements to LTE. The LTE-Advanced will be introduced into Release 10 after a correction and improvement phase in LTE Release 9. The LTE-Advanced shall fulfill requirements as set by ITU (International Telecommunication Union). In LTE-Advanced, the size of UCI (Uplink Control Information, e.g., HARQ-ACK/NACK, CQI (Channel Quality Indicator), SR (Scheduling Request)) will increase due to, e.g., downlink cooperative multipoint (CoMP) transmissions, carrier aggregation, and/or higher order MIMO (Multiple In Multiple Out).
Carrier aggregation, where two or more component carriers are aggregated, is considered for LTE-Advanced in order to support downlink transmission bandwidth larger than 20 MHz, up to 100 MHz (see Non-Patent Document 2 below). From a UE perspective, there is one transport block (in absence of spatial multiplexing) and one HARQ entity per scheduled component carrier. A UE may be scheduled over multiple component carriers and each transport block is mapped within a single component carrier.
Regarding the PUCCH transmission in the LTE-Advanced, several solutions were proposed by some companies (see Non-Patent Document 3). The most straightforward choice is to utilize the same PUCCH structure as in LTE Rel-8 if simultaneous transmission of PUCCH on multiple resource blocks (across different uplink component carriers or within one uplink component carrier) is supported. HARQ ACK/NACK bundling structure, which is the default ACK/NACK feedback mode for TDD (Time Division Duplex) in LTE Rel-8, could be introduced as a solution for PUCCH transmission in LTE-Advanced. In addition, multiplexing structure is also one proposed solution. For multiplexing, multiple HARQ-ACK/NACK feedback bits corresponding to the PDSCHs from different downlink component carriers will be transmitted in one uplink component carrier in the similar way as TDD HARQ-ACK/NACK multiplexing scheme in LTE-Rel-8, which is called as HARQ-ACK/NACK multiplexing using PUCCH format 1b with channel selection.    Non-Patent Document 1: “3GPP TSG RAN E-UTRA Physical layer procedure (Release 8)”, 3GPP TS 36.213 V8.8.0, 2009-09    Non-Patent Document 2: “Carrier aggregation in LTE-Advanced”, 3GPP TSG RAN WG1 Meeting #53bis, R1-082468, June, 2008    Non-Patent Document 3: “Uplink control channel design for LTE-Advanced”, 3GPP TSG RAN WG1 Meeting #56, R1-090629, February, 2009
However, in the above conventional techniques, there is no concrete description on how to assign resources for PUCCH, on which the UCI (e.g., HARQ-ACK/NACK, CQI, SR) for multiple component carriers is transmitted.
All above conventional techniques try to reuse PUCCH structure and resources defined in LTE Rel-8 for the UCI (e.g., HARQ-ACK/NACK, CQI, SR) transmission in LTE-Advanced. However none of them can meet the system requirement well in case of carrier aggregation. Another promising solution is to introduce the PUCCH format (i.e., UCI format) in which the UCI (e.g., HARQ-ACK/NACK, CQI, SR) for multiple component carriers is transmitted. Regarding this solution, the PUCCH resource assignment schemes should be re-considered since the current PUCCH resource assignment in LTE Rel-8 will not be suitable anymore.
The present invention has been made in view of the foregoing circumstances, and its object is to provide a mobile communication method, system, a base station and a user equipment and integrated circuits used therein, which may perform flexible resource assignment for physical uplink control channel, and achieve more efficient transmission control (scheduling) between the eNB (Evolved Node B) and the UE.